let isDone:boolean = false;
let count:number = 10;
let name:string = 'zyy';
let list:number[] = [1,2,3];
// 枚举类型
enum Direction{
    NORTH,
    SOUTH,
    EAST,
    WEST
}

let dir: Direction = Direction.NORTH;
let notSure: any = 666;
notSure = 'z0101';
let value:unknown;

let tupleType: [string, boolean];  // 元组
tupleType = ["zyy", true];

function warnUser():void {}

let u:undefined;
let n:null;